Stainless steel alloy for golf club head

ABSTRACT

A stainless steel alloy adapted for a golf club head includes 0.03 wt % of carbon, 0.01 wt % of phosphorus, 0.1 wt % of silicon, 0.05 wt % of calcium, 0.03 wt % of zirconium, 0.1 wt % of manganese, 0.01 wt % of sulfur, 4 wt % to 5.1 wt % of molybdenum, 18 wt % to 19 wt % of nickel, 7 wt % to 12 wt % of cobalt, 0.05 wt % to 0.15 wt % of aluminum, 0.1 wt % to 0.8 wt % of titanium, and a balance of iron based on 100 wt % of the stainless steel alloy, wherein the content of iron is more than 0 wt %.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority of Taiwanese Patent Application No.102135351, filed on Sep. 30, 2013.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a stainless steel alloy, more particularly to astainless steel alloy adapted for a golf club head.

2. Description of the Related Art

Golf sport involves a player twisting his/her waist to swing a golf cluband strike a golf ball using a golf club head. Thus, in addition tohaving relatively high mechanical strength and abrasion resistance toenhance stroke stability, the golf club head is required to have asuitable weight to minimize player fatigue when swinging the golf club.Furthermore, in order to satisfy general requirements of golfers, anincrease in manufacturing cost needs to be avoided when making the golfclub head with good mechanical strength and abrasion resistance.Therefore, the golf equipment industry has been aggressive in searchingand developing new materials for golf club heads, particularly in alloyshaving different compositions to prepare the golf club head with variousproperties.

Taiwan Patent Publication No. 200630141 discloses an alloy material(referred as a stainless steel alloy hereinafter) for manufacturing thegolf club head. The stainless steel alloy includes carbon in an amountranging from 0.08 wt % to 0.15 wt %, silicon in an amount ranging from0.5 wt % to 1.5 wt %, manganese in an amount ranging from 0.4 wt % to1.2 wt %, copper in an amount less than 0.55 wt %, nickel in an amountranging from 3.5 wt % to 6.0 wt %, chromium in an amount ranging from13.5 wt % to 17.0 wt %, molybdenum in an amount ranging from 1.5 wt % to2.6 wt %, nitrogen in an amount ranging from 0.07 wt % to 0.13 wt %, anda balance of iron based on 100 wt % of the stainless steel alloy. Thegolf club head made from the stainless steel alloy disclosed in TaiwanPatent Publication No. 200630141 has a tensile strength ranging from216.9 ksi to 219.2 ksi (1495.8 Mpa to 1511.7 Mpa), and a yield strengthranging from 175.8 ksi to 180.9 ksi (1212.36 Mpa to 1247 Mpa). However,the overall strength of the golf club head made from the aforesaidstainless steel alloy is not rigid enough to maintain its original shapeand is thus susceptible to deformation.

SUMMARY OF THE INVENTION

Therefore, an object of the present invention is to provide a stainlesssteel alloy for use in a golf club head.

According to a first aspect of this invention, there is provided astainless steel alloy adapted for a golf club head. The stainless steelalloy includes carbon in an amount of 0.03 wt %; phosphorus in an amountof 0.01 wt %; silicon in an amount of 0.1 wt %; calcium in an amount of0.05 wt %; zirconium in an amount of 0.03 wt %; manganese in an amountof 0.1 wt %; sulfur in an amount of 0.01 wt %; molybdenum in an amountranging from 4 wt % to 5.1 wt %; nickel in an amount ranging from 18 wt% to 19 wt %; cobalt in an amount ranging from 7 wt % to 12 wt %;aluminum in an amount ranging from 0.05 wt % to 0.15 wt %; titanium inan amount ranging from 0.1 wt % to 0.8; and a balance of iron based on100 wt % of the stainless steel alloy, wherein the content of iron ismore than 0 wt %.

According to a second aspect of this invention, there is provided astainless steel alloy adapted for a golf club head. The stainless steelalloy includes carbon in an amount ranging from 0.024 wt % to 0.036 wt%; phosphorus in an amount ranging from 0.008 wt % to 0.012 wt %;silicon in an amount ranging from 0.08 wt % to 0.12 wt %; calcium in anamount ranging from 0.04 wt % to 0.06 wt %; zirconium in an amountranging from 0.024 wt % to 0.036 wt %; manganese in an amount rangingfrom 0.08 wt % to 0.12 wt %; sulfur in an amount ranging from 0.008 wt %to 0.012 wt %; molybdenum in an amount ranging from 4 wt % to 5.1 wt %;nickel in an amount ranging from 18 wt % to 19 wt %; cobalt in an amountranging from 7 wt % to 12 wt %; aluminum in an amount ranging from 0.05wt % to 0.15 wt %; titanium in an amount ranging from 0.1 wt % to 0.8 wt%; and a balance of iron based on 100 wt % of the stainless steel alloy,wherein the content of iron is more than 0 wt %.

In the present invention, addition of silicon may increase theflowability of the stainless steel alloy during a forming process.Addition of titanium and molybdenum may enhance the mechanical strengthand abrasive resistance of the stainless steel alloy by virtue of finecrystal grains, so that a golf club head having superior mechanicalstrength and abrasive resistance may be manufactured.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

A stainless steel alloy adapted for a golf club head according to thepresent invention includes:

carbon in an amount ranging from 0.024 wt % to 0.036 wt %, preferablyranging from 0.027 wt % to 0.033 wt %, more preferably ranging from0.0285 wt to 0.0315 wt %, and most preferably of 0.03 wt %;

phosphorus in an amount ranging from 0.008 wt % to 0.012 wt %,preferably ranging from 0.009 wt % to 0.011 wt %, more preferablyranging from 0.0095 wt % to 0.0105 wt %, and most preferably of 0.01 wt%;

silicon in an amount ranging from 0.08 wt % to 0.12 wt %, preferablyranging from 0.09 wt % to 0.11 wt %, more preferably ranging from 0.095wt % to 0.105 wt %, and most preferably of 0.1 wt %;

calcium in an amount ranging from 0.04 wt % to 0.06 wt %, preferablyranging from 0.045 wt % to 0.055 wt %, more preferably ranging from0.0475 wt % to 0.0525 wt %, and most preferably of 0.05 wt %;

zirconium in an amount ranging from 0.024 wt % to 0.036 wt %, preferablyranging from 0.027 wt % to 0.033 wt %, more preferably ranging from0.0285 wt to 0.0315 wt %, and most preferably of 0.03 wt %;

manganese in an amount ranging from 0.08 wt % to 0.12 wt %, preferablyranging from 0.09 wt % to 0.11 wt %, more preferably ranging from 0.095wt % to 0.105 wt %, and most preferably of 0.1 wt %;

sulfur in an amount ranging from 0.008 wt % to 0.012 wt %, preferablyranging from 0.009 wt % to 0.011 wt %, more preferably ranging from0.0095 wt % to 0.0105 wt %, and most preferably of 0.01 wt %;

molybdenum in an amount ranging from 4 wt % to 5.1 wt %;

nickel in an amount ranging from 18 wt % to 19 wt %;

cobalt in an amount ranging from 7 wt % to 12 wt %;

aluminum in an amount ranging from 0.05 wt % to 0.15 wt %;

titanium in an amount ranging from 0.1 wt % to 0.8 wt %; and

a balance of iron based on 100 wt % of the stainless steel alloy,wherein the content of iron is more than 0 wt %.

In addition to precipitate carbide, carbon is an element in a stationaryphase of austenite (referred as α-Fe hereinafter). While carbon contentis increasing, ferrite (referred as γ-Fe hereinafter) is decreasing andα-Fe is more stable.

Silicon could prevent void formation, improve contraction, and enhanceflowability of steel fluid. Therefore, the aforesaid specific amount ofsilicon is added to increase flowability of the stainless steel alloyand improve the alloy casting processability.

Titanium and carbon are liable to form into stable carbide, enhance theprecipitation strengthening of the stainless steel alloy, and inhibitovergrowth of crystal grains in the alloy so as to maintain a relativelyfine size of the crystal grains in the alloy. Therefore, the mechanicalstrength and abrasive resistance of the golf club head made from thestainless steel alloy of the present invention may be improved.

Manganese combines with sulfur easily to eliminate hot shortness that isgenerated by sulfur affecting the stainless steel alloy, and manganesecould remove the oxide in the stainless steel alloy. Therefore,manganese usually coexists with iron. In addition, manganese couldstabilize the α-Fe having FCC (face-centered cubic) structure. When theaforesaid specific amount of manganese is added to the stainless steelalloy of the present invention, the hot shortness may be eliminated andthe alloy casting processability may be improved.

Molybdenum increases hot strength, creep strength and hot hardness ofthe stainless steel alloy, and thus, the golf club head could be made tohave increased abrasion resistance and strength.

Nickel is added to the stainless steel alloy to enhance anticorrosiveand anti-oxidative properties and stabilize the α-Fe having FCCstructure of the stainless steel alloy.

Cobalt is an essential element added to super-hard high-speed steel andnon-super-hard high-speed steel nowadays, and may increase secondaryhardenability, red hardness, and hot hardness. Since cobalt dissolves inα-Fe and γ-Fe to enhance covalent bonds of Co—Fe bond and Fe—Fe bond, nomatter at room temperature or at high temperature, cobalt could enhancea substrate of alloy and raise a melting point of iron-based alloy.

Aluminum is an excellent deoxidizer which could inhibit overgrowth ofthe crystal grain in the stainless steel alloy forming dispersive oxideand nitride, thereby maintaining the stainless steel alloy with a smallgrain size that enhances ductility, workability and toughness of thestainless steel alloy.

Compositions of the stainless steel alloys in Examples 1 to 3 accordingthis invention are listed in Table 1.

TABLE 1 Examples C P Si Ca Zr Mn S Mo Ni Co Al Ti Iron Ex. 1 0.03 0.010.1 0.05 0.03 0.1 0.01 4.0-5.1 18-19 7-12 0.05-0.15 0.1-0.3 63.12-70.52Ex. 2 0.03 0.01 0.1 0.05 0.03 0.1 0.01 4.0-5.1 18-19 7-12 0.05-0.150.3-0.5 62.92-70.32 Ex. 3 0.03 0.01 0.1 0.05 0.03 0.1 0.01 4.0-5.1 18-197-12 0.05-0.15 0.5-0.8 62.62-70.12

The golf club head can be made from the alloy of the present inventionusing a conventional method for fabricating a golf club head thatincludes a former processing stage and a latter processing stage. Theformer processing stage involves precision casting technology, andgenerally includes the steps of mold-making, wax injection, hanging,dipping, dewaxing, casting, cutting, heat treating, etc. The latterprocessing stage includes the steps of surface grinding, washing,lacquering, punching, embedding, assembling, torque testing, polishing,etc.

-   -   The golf club head made from the stainless steel alloy of the        present invention has the following advantages:    -   1. Mechanical strength: manganese, carbon, and titanium were        added to the stainless steel alloys in specific amounts listed        in Table 1, and tensile strength is 1624 MPa and yield strength        is 1616 MPa as shown in Table 2. Therefore, the golf club head        made from the stainless steel alloys of the present invention        may be made with the best conditions for satisfying consumers'        requirements.    -   2. Corrosion resistance: a substantial amount of nickel was        added to the stainless steel alloys to achieve superior        atmospheric corrosion resistance.

Table 2 shows performances of tensile strength, yield strength, andelongation in Examples 1 to 3 and Comparative Example, wherein thestainless steel alloys of the present invention are represented asExamples 1 to 3 and that of the prior art is represented as ComparativeExample. Referring to the results in Table 2, the golf club head madefrom the stainless steel alloys of the present invention has superiortensile strength and yield strength.

TABLE 2 Example and Tensile Yield Comparative strength strengthElongation Density Examples (MPa) (MPa) (%) (g/cm³) Example 1 1624 161610 7.95-8.15 Example 2 1758 1724 12 7.95-8.15 Example 3 2027 1999 117.95-8.15 Comparative 1511 1247 22.4 — Example

To sum up, in the stainless steel alloy adapted for a golf club headaccording to this invention, addition of silicon may increase theflowability in the stainless steel alloy, and addition of titanium andmolybdenum may enhance the mechanical strength of the stainless steelalloy. Moreover, addition of aluminum may stabilize the ductility of thestainless steel alloy, so that the ductility would not be considerablydecreased when the strength of the stainless steel alloy is increased.Accordingly, the golf club head made from the stainless steel alloyaccording to the present invention has comparatively lower processingcost, superior processability, and abrasion resistance relative to thatmade from a conventional stainless steel alloy.

While the present invention has been described in connection with whatare considered the most practical and preferred embodiments, it isunderstood that this invention is not limited to the disclosedembodiments but is intended to cover various arrangements includedwithin the spirit and scope of the broadest interpretation so as toencompass all such modifications and equivalent arrangements.

What is claimed is:
 1. A stainless steel alloy adapted for a golf club head, comprising: carbon in an amount of 0.03 wt %; phosphorus in an amount of 0.01 wt %; silicon in an amount of 0.1 wt %; calcium in an amount of 0.05 wt %; zirconium in an amount of 0.03 wt %; manganese in an amount of 0.1 wt %; sulfur in an amount of 0.01 wt %; molybdenum in an amount ranging from 4 wt % to 5.1 wt %; nickel in an amount ranging from 18 wt % to 19 wt %; cobalt in an amount ranging from 7 wt % to 12 wt %; aluminum in an amount ranging from 0.05 wt % to 0.15 wt %; titanium in an amount ranging from 0.1 wt % to 0.8; and a balance of iron based on 100 wt % of said stainless steel alloy, wherein the content of iron is more than 0 wt %.
 2. The stainless steel alloy according to claim 1, wherein said stainless steel alloy has a density ranging from 7.95 g/cm³ to 8.15 g/cm³.
 3. A stainless steel alloy adapted for a golf club head, comprising: carbon in an amount ranging from 0.024 wt % to 0.036 wt %; phosphorus in an amount ranging from 0.008 wt % to 0.012 wt %; silicon in an amount ranging from 0.08 wt % to 0.12 wt %; calcium in an amount ranging from 0.04 wt % to 0.06 wt %; zirconium in an amount ranging from 0.024 wt % to 0.036 wt %; manganese in an amount ranging from 0.08 wt % to 0.12 wt %; sulfur in an amount ranging from 0.008 wt % to 0.012 wt %; molybdenum in an amount ranging from 4 wt % to 5.1 wt %; nickel in an amount ranging from 18 wt % to 19 wt %; cobalt in an amount ranging from 7 wt % to 12 wt %; aluminum in an amount ranging from 0.05 wt % to 0.15 wt %; titanium in an amount ranging from 0.1 wt % to 0.8 wt %; and a balance of iron based on 100 wt % of said stainless steel alloy, wherein the content of iron is more than 0 wt %.
 4. The stainless steel alloy according to claim 3, wherein: carbon is in an amount ranging from 0.027 wt % to 0.033 wt %; phosphorus is in an amount ranging from 0.009 wt % to 0.011 wt %; silicon is in an amount ranging from 0.09 wt % to 0.11 wt %; calcium is in an amount ranging from 0.045 wt % to 0.055 wt %; zirconium is in an amount ranging from 0.027 wt % to 0.033 wt %; manganese is in an amount ranging from 0.09 wt % to 0.11 wt %; and sulfur is in an amount ranging from 0.009 wt % to 0.011 wt %, based on 100 wt % of said stainless steel alloy.
 5. The stainless steel alloy according to claim 4, wherein: carbon is in an amount ranging from 0.0285 wt to 0.0315 wt %; phosphorus is in an amount ranging from 0.0095 wt % to 0.0105 wt %; silicon is in an amount ranging from 0.095 wt % to 0.105 wt %; calcium is in an amount ranging from 0.0475 wt % to 0.0525 wt %; zirconium is in an amount ranging from 0.0285 wt to 0.0315 wt %; manganese is in an amount ranging from 0.095 wt % to 0.105 wt %; and sulfur is in an amount ranging from 0.0095 wt % to 0.0105 wt %, based on 100 wt % of said stainless steel alloy. 